175 research outputs found
Three-dimensional isotropic perfect lens based on LC-loaded transmission lines
An isotropic three-dimentional perfect lens based on cubic meshes of
interconnected transmission lines and bulk loads is proposed. The lens is
formed by a slab of a loaded mesh placed in between two similar unloaded
meshes. The dispersion equations and the characteristic impedances of the
eigenwaves in the meshes are derived analytically, with an emphasis on
generality. This allows designing of transmission-line meshes with desired
dispersion properties. The required backward-wave mode of operation in the lens
is realized with simple inductive and capacitive loads. An analytical
expression for the transmission through the lens is derived and the
amplification of evanescent waves is demonstrated. Factors that influence
enhancement of evanescent waves in the lens are studied and the corresponding
design criteria are established. A possible realization of the structure is
outlined.Comment: 22 pages, 15 figure
Experimental verification of the key properties of a three-dimensional isotropic transmission line based superlens
Design and experimental realization of a three-dimensional superlens based on
LC-loaded transmission lines are presented. Commercially available components
and materials are used in the design. Transmission properties of the designed
structure are studied experimentally and the observed lens properties are
compared with analytical predictions. Backward-wave propagation and
amplification of evanescent waves in the prototype structure are verified both
analytically and experimentally.Comment: 12 pages, 10 figure
On Artificial Magneto-Dielectric Loading for Improving the Impedance Bandwidth Properties of Microstrip Antennas
In the present paper we discuss the effect of artificial magneto-dielectric
substrates on the impedance bandwidth properties of microstrip antennas. The
results found in the literature for antenna miniaturization using magnetic or
magneto-dielectric substrates are revised, and discussion is addressed to the
practically realizable artificial magnetic media operating in the microwave
regime. Using a transmission-line model we, first, reproduce the known results
for antenna miniaturization with non-dispersive material fillings. Next, a
realistic dispersive behavior of a practically realizable artificial substrate
is embedded into the model, and we show that frequency dispersion of the
substrate plays a very important role in the impedance bandwidth
characteristics of the loaded antenna. The impedance bandwidths of reduced size
patch antennas loaded with dispersive magneto-dielectric substrates and
high-permittivity substrates are compared. It is shown that unlike substrates
with dispersion-free permeability, practically realizable artificial substrates
with dispersive magnetic permeability are not advantageous in antenna
miniaturization. This conclusion is experimentally validated.Comment: 22 pages, 14 figures, 5 tables, submitted to IEEE Trans. Antennas
Propaga
Near-field enhancement and imaging in double cylindrical polariton-resonant structures: Enlarging perfect lens
We experimentally demonstrate a prototype of a cylindrical enlarging lens
capable of enhancing and restoring evanescent fields. The enabling phenomenon
is the resonant excitation of coupled surface modes in a system of two
cylindrical arrays of small resonant particles. As was shown in [J. Appl. Phys.
96, 1293 (2004)], this phenomenon in planar arrays can be used in
electromagnetic near-field imaging. Here, we use a similar structure in a
cylindrically symmetric configuration, which gives us a possibility to obtain
an enlarged near-field image.Comment: 7 pages, 4 figure
Experimental demonstration of sub-wavelength image channeling using capacitively loaded wire medium
In this letter we experimentally demonstrate a possibility to achieve
significant sub-wavelength resolution of a near-field image channeled through a
layer of an electromagnetic crystal. An image having radius of has
been realized using an electrically dense lattice of capacitively loaded wires.
The loading allows to reduce the lattice period dramatically so that it is only
a small fraction of the free-space wavelength. It is shown that losses in the
structure only decrease the total amplitude of the image, but do not influence
the resolution.Comment: 4 pages, 7 figures, submitted to PR
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